Selectable control for high intensity LED illumination system to maintain constant color temperature on a lit surface

ABSTRACT

A lighting system includes a group of light emitting diode (LED) illumination devices, each of which includes a device driver. One or more sensors are configured to measure a characteristic of light received from the devices in an area of an environment that is illuminated by the devices. A controller detects when a value of the measured light characteristic received by a sensor deviates from a desired value. When this happens, the controller will cause the device drivers for each of the LED illumination devices to control LEDs in each illumination device so that the desired color temperature of light will be received at the location of the sensor while maintaining a substantially constant illuminance level at the location.

RELATED APPLICATIONS AND CLAIM OF PRIORITY

This patent document claims priority to U.S. Provisional PatentApplication No. 61/917,054, filed Dec. 17, 2013, the disclosure of whichis fully incorporated into this document by reference.

The patent document is related to U.S. patent application Ser. No.14/573,553, U.S. patent application Ser. No. 14/573,584, U.S. patentapplication Ser. No. 14/573,619 and U.S. patent application Ser. No.14/573,668, each filed Dec. 17, 2014. The disclosures of each relatedapplication are fully incorporated into this document by reference.

BACKGROUND

Entertainment facilities such as stadiums, arenas and concert halls seekways to offer unique experiences with lighting and special effects.However, the current methods of providing such effects through lightinghave been limited because of the manual operation required to changecolors, intensities and positions associated with overhead lightfixtures. In addition, the ability to rapidly change lighting effects islimited due to the significant amount of time that it takes to start andilluminate high intensity discharge fixtures, such as high intensitydischarge lamps. Further, because of the amount of light required to beemitted by many stadium lights, the lights may require a significantamount of energy and may generate a substantial amount of heat.

In addition, in certain facilities such as stadiums and sports arenas,the events that occur in the arena have very specific lightingspecifications. For example, a hockey league may require relatively coollight of a color temperature of approximately 5500K, while a concert maydesire a slightly warmer light of a color temperature of approximately4000K. It is very expensive for facilities to maintain a variety oflight fixtures to meet all of these specifications.

This document describes new illumination devices and control systemsthat are directed to solving the issues described above, and/or otherproblems.

SUMMARY

In an embodiment, a lighting system includes a group of light emittingdiode (LED) illumination devices, each of which includes a first groupof LEDs of a first color temperature and a second group of LEDs of asecond color temperature. The system also includes illumination devicedrivers, wherein each illumination device driver is configured tocontrol a corresponding LED illumination device. One or more sensors areconfigured to measure a characteristic of light received from theillumination devices in an area of an environment that is illuminated bythe devices. A wireless transmitter may be electrically connected to thesensor and configured to transmit measurements detected by the sensor. Acontroller may include a processor and programming instructions on acomputer-readable medium (i.e., as software or firmware) that areconfigured to cause the processor to detect when a value of the measuredlight characteristic received by a sensor deviates from a desired value.In response to detecting that the value of the measured lightcharacteristic deviates from the desired value, the controller willgenerate commands to cause the device drivers for each of the LEDillumination devices to control the first group of LEDs and the secondgroup of LEDs in its corresponding illumination device so that thedesired color temperature of light will be received at the location ofthe sensor while maintaining a substantially constant illuminance levelat the location.

The commands that cause the device drivers to control the first group ofLEDs and the second group of LEDs in each illumination device so thatthe desired color temperature of light will be received at the locationmay include instructions to increase the drive current delivered to thefirst group of LEDs and decrease the drive current delivered to thesecond group of LEDs in each illumination device. The commands thatcause the device drivers to control the first group of LEDs and thesecond group of LEDs so that the illuminance level remains substantiallyconstant may include commands to: (i) automatically reduce thebrightness of one of the groups of LEDs by decreasing a width of voltagepulses applied to that group of LEDs or increasing spacing betweenvoltage pulses applied to that group of LEDs; and (ii) automaticallyincrease the brightness of the other group of LEDs by increasing a widthof voltage pulses applied to that group of LEDs or decreasing spacingbetween voltage pulses applied to that group of LEDs.

If the sensors include a light intensity sensor, then when a value ofmeasured light intensity exceeds a threshold, the device drivers mayreduce the brightness of a group of the LEDs by decreasing a width ofvoltage pulses applied to the group of LEDs or increasing spacingbetween voltage pulses applied to the group of LEDs to maintain anilluminance level at the location within the threshold. When the valueof measured light intensity is below the threshold, the device driversmay automatically increase the brightness of a group of the LEDs byincreasing a width of voltage pulses applied to the group of LEDs or bydecreasing spacing between voltage pulses applied to the group of LEDsto maintain the illuminance level at the location within the threshold.

If the sensor(s) include a color temperature sensor, then when a valueof color temperature detected by the sensor has moved above or below athreshold, the system may control drive currents delivered to the firstgroup of LEDs and the second group of LEDs so that the light detected bythe sensor at the location will exhibit a color temperature that iswithin the threshold. To maintain the substantially constant illuminancelevel at the location, the system may reduce the brightness of one ofthe groups of LEDs by decreasing a width of voltage pulses applied tothat group of LEDs or increasing spacing between voltage pulses appliedto that group of LEDs, and it may increase the brightness of the othergroup of LEDs by increasing a width of voltage pulses applied to thatgroup of LEDs or decreasing spacing between voltage pulses applied tothat group of LEDs.

If the sensor(s) include a D_(uv) sensor, then when the value of D_(uv)detected by the sensor has moved above or below a threshold, the systemmay control drive currents delivered to the first group of LEDs and thesecond group of LEDs so that the light emitted by all of the LEDs willexhibit a D_(uv) that is within the threshold. To maintain thesubstantially constant illuminance level at the location, the system mayagain reduce the brightness of one of the group of LEDs by decreasing awidth of voltage pulses applied to that groups of LEDs or increasingspacing between voltage pulses applied to that group of LEDs, and it mayincrease the brightness of the other group of LEDs by increasing a widthof voltage pulses applied to that group of LEDs or decreasing spacingbetween voltage pulses applied to that group of LEDs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a lighting system and control devicesfor such a system.

FIG. 2 illustrates a front view of an example of one embodiment of anillumination device that may be used with the system disclosed in thisdocument.

FIG. 3 illustrates a perspective view from a side of the device of FIG.2.

FIG. 4 illustrates an embodiment of the device with an expanded view ofan LED module.

FIG. 5 illustrates an example of an LED array on a substrate, with acontrol card.

FIGS. 6A and 6B illustrate data that may be used for color tuning of anLED lighting device.

FIG. 7 illustrates an example of a user interface device.

FIG. 8 illustrates example components that may receive signals andselectively control LED groups.

FIG. 9 illustrates example components of an electronic device that mayimplement a user interface.

FIG. 10 illustrates an example of an environment in which lightingdevices and sensors may be used in the context of various embodiments.

FIG. 11 illustrates an example of duty cycling of the LEDs using pulsewidth modulation (PWM), according to an embodiment.

DETAILED DESCRIPTION

As used in this document, the singular forms “a,” “an,” and “the”include plural references unless the context clearly dictates otherwise.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. As used in this document, the term “comprising” means“including, but not limited to.”

When used in this document, the terms “upper” and “lower,” as well as“vertical” and “horizontal,” are not intended to have absoluteorientations but are instead intended to describe relative positions ofvarious components with respect to each other. For example, a firstcomponent may be an “upper” component and a second component may be a“lower” component when a light fixture is oriented in a first direction.The relative orientations of the components may be reversed, or thecomponents may be on the same plane, if the orientation of a lightfixture that contains the components is changed. The claims are intendedto include all orientations of a device containing such components.

FIG. 1 illustrates a lighting system in which any number of lightingdevices 10 a, 10 b, 10 c are positioned at various locations in anenvironment, such as a wall, ceiling, mast, tower or other supportingstructure in a stadium, arena, concert hall, outdoor amphitheater orother entertainment facility or other location. Each illumination devicemay include a number of light emitting diodes (LEDs), and in variousembodiments a number of LEDs sufficient to provide a high intensity LEDdevice. Each illumination device may include or be connected to a devicecontroller 210(a), 210(b), 210(c) that includes wiring and circuitry tosupply power and/or control signals to one or more lights. A devicecontroller may be an external device, or an integral device thatincludes various components of an illumination device's control card.Each device controller 210(a), 210(b), 210(c) may include a receiverthat receives wireless signals from one or more transmitters. Thetransmitters may be included in, for example, one or more user interfacedevices 202.

Each interface device 202 may include selectable user inputs,programming, a processor or circuitry, and a transmitter fortransmitting command signals to the various illumination devices. Forexample, the user inputs may include inputs to turn certain lights in acertain zone of an environment on or off, in which case the interfacedevice will generate and send signals with encoded data that instructthe zone's lights to turn on and off. The user inputs also may includebrightness level adjustments for one or more zones and/or lights, orscenes that are designed to set various lighting devices at variousbrightness levels. Each user input command will cause the user interfacedevice to send a signal that includes data indicating which illuminationdevices should be operated by the signal. When a control device detectsa signal that is intended for its illumination device, it will cause itsillumination device to execute the command that corresponds to thecontrol signal.

In addition, any number of external light sensors 205 a-205 n may bepositioned at a location or multiple locations in an environment, suchas a stadium playing field, a stage in a concert hall, or acourt/floor/ice rink in an area, to detect one or more characteristicsof light. The external light sensors may include transmitters that sendstatus information and/or commands to any or all of the illuminationdevice controllers and/or the interface device. For example, aparticular illumination device controller 210 c may be programmed todetect signals from a particular sensor 205 a that is positioned in anarea at which the controller's corresponding light fixture 10 c directslight. The sensor may sense light intensity, color temperature and/orcolor rendering index (CRI) in its vicinity and transmit intensity datato the device controller 210 c. The device controller 210 c may beprogrammed to increase the LED device's 10 c brightness if the localintensity data is less than a threshold, or it may decrease the LEDdevice's 10 c brightness if the local intensity data is greater than athreshold. As described above, the controller may do this by increasingor decreasing the frequency of “on” signals that cycle the LEDs on andoff by PWM. Alternatively, the sensor 205 a itself may includeprogramming and electronics that cause it to send a command to thecontroller 210 c, such as an increase brightness command if localintensity is less than a threshold level or a decrease brightnesscommand if local intensity is greater than a threshold level.

It is intended that the portions of this disclosure describing LEDmodules and control systems and methods may include various types ofdevices. For example, the LED modules, control systems and controlmethods may include those disclosed in International Patent ApplicationNo. PCT/US2012/069442, filed Sep. 13, 2012 by Nolan et al., thedisclosure of which is incorporated herein by reference in its entirety.FIG. 2 illustrates a front view of an example of one embodiment of anillumination device that may be used with this system. FIG. 3illustrates a perspective view from one side of the device of FIG. 2.The illumination device 10 includes a housing 25 that encases variouscomponents of a light fixture. The housing 25 includes an opening inwhich a set of light emitting diode (LED) array modules 11-14 aresecured to form a multi-array LED structure 18. The LED array modules11-14 are positioned to emit light away from the fixture. The openingalso provides a sensor compartment 15, which may be enclosed, open orpartially open, and via which one or more sensors may detect informationabout the environment exterior to the device. The sensors may includesensors that detect light, ambient temperature, color temperature orother properties of the ambient area in front of the LED array modules11-14.

The opening of the housing 25 may be circular as shown, with the sensorcompartment 15 for the sensors positioned at the center of the circleand the LED array modules 11-14 positioned around the central opensection to form a ring-shaped overall LED structure, although othershapes and configurations are possible. The LED arrays 11-14 may includefour arrays, each of which is positioned in a quadrant of the circle asshown. Alternatively, any other number of LED array modules, such asone, two, three, five or more LED array modules, may be positionedwithin the opening in any configuration.

The device's housing 25 includes a body portion 27 and an optionalshroud portion 29. The body portion 27 serves as a heat sink thatdissipates heat that is generated by the LED arrays. The body/heat sink27 may be formed of aluminum and/or other metal, plastic or othermaterial, and it may include any number of fins 22 a . . . 22 n on theexterior to increase its surface area that will contact a surroundingcooling medium (typically, air). Thus, the body portion 27 may have abowl shape as shown, the LED array structure 18 may fit within theopening of the bowl, and heat from the LED array modules 11-14 may bedrawn away from the array and dissipated via the fins 22 a . . . 22 n onthe exterior of the bowl. In addition, the housing may include a shroud29 that extends from the body 27 and beyond the LED array module. Theshroud may be semi-circular in shape when the multi-array LED structureis circular, and it may be angled or shaped to shield an upper portionof the light assembly from rain while directing, focusing and/orreflecting light so that the light is concentrated in a desireddirection (e.g., downward).

While the LED array is positioned at one side of the body 27, theopposing side of the body may include a power supply 30. The powersupply 30 may include a battery, solar panel, or circuitry to receivepower from an external and/or other internal source. As shown, theexternal housing of the power supply 30 also may include fins to helpdissipate heat from the power supply. Power wiring may be positionedwithin the body 27 to direct power from the power supply 30 to the LEDarray modules 11-14. The power supply housing 30 and/or a portion of thelighting unit housing 25 may include one or more antennae, transceiversor other communication devices 35 that can receive control signals froman external source. For example, the illumination device may include awireless receiver and an antenna that is configured to receive controlsignals via a wireless communication protocol.

The housing may be attached to a support structure 40, such as a base ormounting yoke, optionally by one or more connectors 41. As shown, theconnectors 41 may include axles about which the housing and/or supportstructure may be rotated to enable the light assembly to be positionedto direct light at a desired angle.

When the LED array operates, heat generated by the LEDs will rise anddissipate through the heat sink, creating a negative pressure that maydraw cool ambient air into the housing via an opening near the sensorcompartment 15. This chimney effect helps keep the LED array structureunit cool during operation. FIG. 3 also illustrates that the shroud 29may have a variable width so that an upper portion positioned at the topof LED structure 18 is wider than a lower portion positioned at thebottom of the LED structure. This helps to reduce the amount of lightwasted to the atmosphere by reflecting and redirecting stray lightdownward to the intended illumination surface.

FIG. 4 illustrates an embodiment of the device, with an expanded view ofone of the LED array modules 12 of the LED structure 18. As shown, themodule 12 includes a conductive substrate 38 on which a number of LEDs39 are positioned. The LEDs 39 may be arranged in one or more rows,matrices, or other arrangements with corresponding components supportedin place and/or spaced apart by supports. For example, the LEDs may formmatrices of n×n LEDs, such as 4×4 or 8×8 matrices. Alternatively, asshown in FIG. 4, the LEDs in each module 12 may be positioned in curvedrows so that when all modules are positioned within the opening, the LEDstructure 18 comprises concentric rings of LEDs. The substrate 38 mayinclude a portion that is a printed circuit board. Driver circuitry onthe circuit board may deliver current to the LEDs, and the LED arraymodules may include multi-wire connectors with prongs and/or receptaclesfor connecting to external conductors and/or signal wires, or other LEDarray modules. A lens cover 41 may be positioned over the substrate 38to protect the substrate 38 and LEDs 39 from the ambient elements, aswell as to focus and/or direct light emitted by the LEDs 39.

FIG. 5 illustrates an example of a portion of an LED array module 134.The LED array module includes any number of LEDs 164. The LEDs may bearranged in rows, matrices, or other arrangements with correspondingcomponents supported in place and/or spaced apart to form modules of anynumber of LEDs. The LEDs may be arranged and mounted on a circuit board160. Driver circuitry on the circuit board 160 may deliver current tothe LEDs, and the LED array modules may include multi-wire connectorswith prongs and/or receptacles for connecting to external conductorsand/or signal wires, or other LED array modules.

One or more circuit control cards 55 may be positioned under, adjacentto or otherwise near the LED array modules to provide power to the LEDs.The LEDs to which power is supplied may be selectively controlled bycontrol circuitry such as that described below in this document. Thecontrol card may include a supporting substrate made of a material suchas fiberglass, and a non-transitory computable-readable memory forstoring programming instructions and/or monitored data and/oroperational history data, one or more processors, a field programmablegate array (FPGA), application specific integrated circuit (ASIC) orother integrated circuit structures, and a received for receivingcontrol signals from an external transmitter. The LED array assembly 134and control card 55 may be placed within an opening of one end of thehousing body.

The circuitry of the control card 55 and or the LED array module 134 mayoperate to maintain a constant current draw across the LEDs andautomatically adjust the intensity of the emitted light in response tofeedback collected by the sensors. For example, each LED array module134 may be arranged so that groups of LEDs are electrically connected inseries. Each group may be served by a programmable system on a chip(SoC) 174 which serves to receive a command from telemetry and send dutycycle information to multiple strings of LEDs.

Optionally, any LED module may include several LED strings or groups ofdifferent colors. For example, a module may include a red (R) LEDseries, a green (G) LED series, a blue (B) LED series, and a white (W)LED series. If so, the color of light emitted by the unit may beselectably controlled by the control card in response to externalcommands as described below. In addition or alternatively, some, all, orportions of the LED arrays may include white LEDs of differenttemperatures so that they can be selectively driven at different levelsto produce variable temperature white light from the same fixture. Inaddition, any LED module may include various strings or groups, all ofwhich emit white light, but which collectively exhibit a variety ofcolor temperatures. For example, various LED lamps may have LEDs rangingfrom about 2700K to about 6500K, from about 4000K to about 6500K, somein a range around 5000K, or other ranges and combinations. The differenttypes of LEDs may be relatively evenly distributed throughout thedevice's LED structure so that the device exhibits a uniform appearancewhen it emits light.

To control the color or color temperature of light directed to aparticular area of an environment, the system's interface device (202 inFIG. 1) may include or be in communication with a processor andcomputer-readable memory containing programming instructions that enablea user to selectably control the light emitted by the variousillumination devices. For example, the environment may be divided into anumber of zones, and each illumination device may be assigned to one ormore of the zones. When the system receives a command to direct light ofa specified color or color temperature to a particular zone, it mayidentify the illumination devices that should be activated and send asignal containing instructions to the controllers (210 a . . . 210 n inFIG. 1) for the illumination devices associated with that zone. Eachcontroller may then send a signal to the control card (55 in FIG. 5) ofits associated illumination device to selectively activate a group ofthe devices LED's that will cause the device to emit light of thedesired color or color temperature.

The interface device, controllers, and/or control cards may, whengenerating their output, identify what drive currents to apply tovarious groups of LEDs to achieve the desired color or colortemperature. The selection of color temperatures for LEDs may vary basedon the groups of LEDs that are available in the device. For example, anillumination device may have a first group of 100 LEDs having a colortemperature of 4000K and second group of 100 LEDs having a colortemperature of 6500K. If the system receives a command to emit light ata specified color temperature, it may use an algorithm, reference alookup table, or use other suitable methods to determine what drivecurrents to apply to each group of LEDs to achieve the desiredtemperature. As a simple example, as illustrated in FIG. 6A, the systemmay have a table or algorithm that identifies drive currents to apply tothe 4000K LEDs (represented by line 603) and the 6500K LEDs (representedby line 601) to a achieve a desired color temperature. Each line mayrelate to a particular LED drive circuit, as will be described in moredetail below in the discussion of FIG. 7. Different drivers may exhibitdifferent characteristics, and the slope and other characteristics ofthe lines shown in FIG. 6A may vary based on the driver chip that isused. The system may perform diagnostics on a chip to learn thisinformation during an initialization process, or this information may beentered as a data file or manually and then stored for use duringoperation of the lighting system.

In the example of FIG. 6A, if the desired output is a color temperatureof 5000K, the system may drive the 4000K LEDs at a current of 1250 maand the 6500K LEDs at a drive current of about 900 ma. FIG. 6Billustrates what luminous flux may result from achieving various colortemperatures. Thus, desired luminous flux could be as an input, and thesystem may then determine the color temperature that would yield theluminous flux, and then look up or calculate the required drive currentsto achieve the desired luminous flux. FIG. 6B also illustrates plateauparameters at which a light may operate and maintain a substantiallyconstant luminance level. Operating the light in accordance with theparameters in the plateau area may yield a substantially constantluminance level.

In some embodiments, the system may be operated to maintain a constantlight output from one or more groups of LEDs so that the light level asmeasured using any suitable unit of measure, such as lumens output bythe light or footcandles measured by one or more sensors positioned atvarious locations in the lighting environment (e.g., playing field,stage, etc.). Each of these units may be referred to in this document as“luminance” or “intensity” of light, or “illuminance” in the context ofan area. All such terms may be used interchangeably in this document,such that a one of these values will be equivalent to another one ofthese values. Maintenance of substantially constant illuminance mayenable the system to maintain substantially constant light levels in allareas of the environment, even while the colors of the light arechanging.

In some embodiments, the system also may include a data storage facilitycomprising sets of scene data. When a user interface receives aselection of a scene, the system may access the data storage facilityand retrieve a set of scene data that corresponds to the selected scene.It may then extract an identification of the group of LED devices thatcorrespond to the selected scene from the retrieved scene data. Thesystem also may identify a color selection for each multi-color devicein the group having LEDs by, for each such LED device, identifying afirst group of LEDs of a first color temperature and a second group ofLEDs of a second color temperature. Then, for each of the LED devicesthat correspond to the group, the system identify a first drive currentfor the first group of LEDs and a second drive current for the secondgroup of LEDs. The combination of first and second drive currents willcause the system to operate at a substantially constant luminance leveland a desired overall color temperature.

In some embodiments, the system may include a user interface via which auser may define or select a scene. FIG. 7 illustrates an example of sucha device 700, in which a set of activators 703 such as buttons, knobs,switches, touch-screen display elements or other user selectableinterface elements supported by a housing 701 and which are configuredto enable a user to select a scene or define a scene. When a userselects any of the interface elements to request that a set of lightsprovide a defined scene, circuitry or programming may cause the deviceto transmit, optionally via a wireless transmitter 709, a command to thedevice drivers to adjust their settings to implement the scene. Thescene may include desired color temperatures, intensities, or otherlight characteristics at various sections of an environment such as anarena, concert hall, stadium, theater, convention center room, stage, orother area that is to be lit. As noted above, the user interface is anelectronic device and/or a software module running on an electronicdevice that includes inputs by which a user may enter commands that thesystem will use to selectably control lights. The user interface 700 mayhave multiple pre-programmed inputs that call for pre-defined scenes.When the desired scene is selected, the user interface may acquire thelookup table or algorithm itself, such as by retrieving it from a localmemory or a networked or cloud-based data storage facility.Alternatively, the user interface 700 may send a unique identifier forthe scene to one or more lighting devices with which it is incommunication, and each device could then use that identifier to couldacquire the lookup table or algorithm and establish the settings foreach lighting device that match the identified scene.

For example, referring to FIG. 8, the system may include a receiver 811that receives commands and monitored data signals from an external wiredor wireless communication device. The receiver may pass the commands toa master control unit 812, such as a processor that implements softwareor firmware, a computing device, or a programmable system-on-a chip thatstores information that can be used to selectively activate variousdrivers 801-804 that each control current to one or more sets of LEDs.Each driver 801-804 may control a separate illumination device, or agroup of LEDs within a particular illumination device. The devices mayreceive power via a converter 821 which is protected from voltage orcurrent variances by an input protection device 822 such as a surgeprotector. The receiver also may include input protection 810 such as afirewall or device that protects the receiver against receiving and/orpassing to the master control unit unauthorized signals.

The selection of which LED drivers to activate, and at what level, maybe determined in real time by the system based on the input of a desiredcolor temperature, intensity or other characteristic of light in aparticular zone. For example, the receiver 811 may receive a desiredtemperature and pass it to the master controller 812, which will alsoreceive monitored data from the zone (such as light intensity or colortemperature) and generate commands to select, or increase or decreasecurrent to, a particular group of LEDs for an illumination device thatis directed to that zone if the monitored data indicates that the lightintensity or color temperature in the zone is below or above the desiredtemperature by at least a threshold amount. Alternatively, the variouscommands and drive currents may be stored in a computer-readable memoryin association with various scenes, and the system may issue commandscorresponding to a scene when a user selects a particular scene.

For example, consider the implementation discussed above of anillumination device having a two strings of LEDs, one with a 4000K colortemperature (CCT) and one with a 6500K CCT. The master controller may beprogrammed to use a formula to select the group of LEDs to drive toachieve the desired temperature. The system may use a set of equationsto balance the total light output such as:

drive current for 4000K LEDs=−3242.21n(Desired CCT)−26892; and

drive current for 6500K LEDs=−33121n(Desired CCT)+29674;

whereby the system sets the drive currents applied to the LED groups ineach affected lighting device so that (4000K drive current)+(6500K drivecurrent) is always less than or equal to a maximum total drive currentof 2300 mA.

When the system receives a command to change the color temperatureoutput by the light, the system may automatically adjust the lightintensity directed to the environment by increasing or decreasing thedrive current for some or all of the LEDs that are used to operate atthe new color temperature. For example, the system may use the twoequations to balance the total light output of the fixture or group offixtures, so that as one string of LEDs is driven with higher current,an adjacent string (or another selected string) is driven with lesscurrent. Selection of other color temperature LEDs may require adifferent set of equations. The equations may be implemented insoftware, firmware, programmed onto a chip, or applied in a customcontrol interface which then sends the commands to the master controllervia the receiver. A user may fine tune the color temperature by using auser interface (such as a control device) to increase or decrease adesired CCT. The system may then increase the drive current in one groupof LEDs having a first color temperature, while simultaneouslydecreasing the drive current in a second group of LEDs having adifferent color temperature, to achieve the desired CCT output and lightintensity.

As noted above, various sensors, such as light intensity, colorrendering index (CRI) sensors, D_(uv) sensors, and/or color temperaturesensors, may be located on the playing surface, stage, or other lightingenvironment. The sensors may be arranged in any suitable arrangement,such as a grid. The sensors may be either permanently installed, orportable to be installed temporarily for calibration events. Oncesensors are in place, an optional calibration event may begin. In thecalibration event, all data will be acquired in a zone through one dataacquisition event. Both light intensity and color temperature in thelighting environment, as well as other parameters such as CRI or D_(uv)may be acquired at this time. Zone size will be dependent on the numberand placement of sensors.

The sensors may be in electronic communication with a master controller.Once data is acquired by the sensors, to continue the calibration theymay send the information to the controller (such as the mastercontroller, or another processing device), which will perform acalculation that uses the received intensity or color temperatureinformation and a reference level as variables and determines whether orhow much to change (increase or decrease) the drive current to apply toeach luminaire (or individual sets of LEDs within a luminaire) that ispositioned to direct light to that zone. An example equation used inthis scenario follows:

${\Delta\;{Drive}\mspace{14mu}{Current}} = {1.33 \times {\frac{\left( {{{Target}\mspace{14mu}{Intensity}} - {{Acquired}\mspace{14mu}{Intensity}}} \right)}{\left( {{Acquired}\mspace{14mu}{Intensity}} \right)}.}}$

In this equation, the target intensity is a user- or system-specifiedintensity that is to be maintained in the zone, and the acquiredintensity is a sum, average, mean or other composite function of theintensity levels acquired by the sensors in the zone. Other equationsmay be used in various embodiments. The calibration process may be doneduring initial facility setup, when initiated later by a user or by afacility change, or in some embodiments automatically at periodicintervals.

The system may then automatically implement the change, and repeat themeasuring and adjustment process until the desired color temperature andlight intensity are achieved. The system may do this for a group ofdesired color temperatures and light intensities, and it may store thisinformation in a data storage facility as a data set, such as a lookuptable. Then, when the system receives a command to cause light of adesired intensity or color temperature to appear in a zone it mayretrieve that data and use it to select the appropriate illuminationdevices and LED groups to drive, and at what level.

For example, when a user enters a command in the user interface tochange the applied scene, or to change the color temperature of lightemitted in a zone or by a specific device, the system may select theLEDs to be driven, and drive currents to be applied to each LED group,by looking up the data stored in the calibration process. The sameprocess may occur if a sensor detects that a light characteristic at aparticular location has deviated from a threshold level or range. If theselected or threshold color temperature for a group of LEDs does nothave associated drive currents stored in the memory, the system maycalculate appropriate drive currents using algorithms such as thosedescribed above. It may also update the data in the memory to includethe newly-calculated drive currents.

In an option where the control card controls the LEDs by pulse widthmodulation (PWM), an oscillating output from the processor repeatedlyturns the LEDs on and off based by applying a pulsed voltage. Each pulseis of a constant voltage level, and the control circuitry varies thewidth of each pulse and/or the space between each pulse. When a pulse isactive, the LEDs may be turned on, and when the pulses are inactive theLEDs may be turned off. If the duty cycle of the “on” state is 50%, thenthe LEDs may be on during 50% of the overall cycle of the control pulses(as shown in FIG. 11). The pulses are delivered rapidly so that thehuman eye does not detect a strobing effect at least 24 pulses persecond. The control card may dim the lights by reducing the duty cycleand effectively extending the time period between each “on” pulse—sothat the LEDs are off more than they are on. Alternatively, the controlcard may increase the brightness of the LEDs by increasing the dutycycle. The system may selectively change the PWM applied to a lightingdevice when it changes other characteristics (such as CCT) in order tomaintain substantially constant illuminance in an area while changingthe CCT or other characteristics.

The control card may receive data from the various sensors in theenvironment and apply that data to a rule set to determine whether toincrease, decrease, or maintain the intensity of the LEDs. For example,if a sensor detects that the illuminance of light in the vicinity of thesensor exceeds a threshold, the control card may receive thisinformation and in response cause the LEDs to dim by reducing thevoltage output of each transformer and/or reducing the duty cycle of theLEDs in the module. When used in this document, the term “threshold” mayrefer to a value, or it may refer to a range of values with an upper andlower value. Each such option is intended to be included within thescope of the term.

For example, an illumination device may have a first set of LEDs havinga CCT of 4000K and second set of LEDs having a CCT of 6500K. The lightfixture control card may include programming to maintain the lightemitted by the device at a threshold level or threshold range. When thesensor detects that the emitted light exceeds or falls below thethreshold, the control card may implement a process that applies analgorithm, references a lookup table, or use other suitable methods todetermine what drive currents to apply to each of the groups of LEDs toachieve the desired CCT. For example, if the desired output is a CCT of5000K, the system may drive the 4000K LEDs at a current of 1250 ma andthe 6500K LEDs at a drive current of about 900 ma. The same process or asimilar process may be applied when the sensor measures D_(uv). Thealgorithms and lookup table amounts may be set so that the system doessubstantially change the illuminance level measured by light intensitysensors in the sensor department when the drive current changes areimplemented.

Alternatively, the system may maintain the output of each illuminationdevice even as the lighting source degrades over time due to dustcollecting on the lenses, yellowing of the lenses caused by exposure toultraviolet (UV) light, movement of the light, or other factors. To dothis, as illustrated in FIG. 1, various sensors 205 a . . . 205 n maymonitor properties of the light emitted. When the system determines thatthe intensity of light in an area has been reduced to a threshold, or byat least a threshold amount over a time period, it may alert theinterface device 202 and/or controllers 210 a . . . 210 n, which inresponse may generate commands that cause the control cards of therelevant illumination device to increase the current delivered to LEDs,this increasing their output.

FIG. 9 depicts an example of internal hardware that may be used tocontain or implement the various processes and systems as discussedabove that relate to a user interface and/or controller. An electricalbus 900 serves as an information highway interconnecting the otherillustrated components of the hardware. A computing device will includeone or more processors. CPU 905 is a central processing unit of thesystem, performing calculations and logic operations required to executea program. CPU 905, alone or in conjunction with one or more of theother elements disclosed in FIG. 9, is a processing device, computingdevice or processor as such terms are used within this disclosure. Asused in this document, the terms “processor” and “processing device” mayinclude a single processor or a group of processors that collectivelyperform various steps of a process. Read only memory (ROM) 910 andrandom access memory (RAM) 915 constitute examples of memory devices. Asused in this document, the terms “computer-readable medium,” “memory” or“memory device” are used interchangeably and may include a single memorydevice, a group of memory devices, or a sector or other subdivision ofsuch a device.

A controller 920 interfaces with one or more optional memory devices 925that service as data storage facilities to the system bus 900. Thesememory devices 925 may include, for example, an external DVD drive or CDROM drive, a hard drive, flash memory, a USB drive, a distributedstorage medium such as a cloud-based architecture, or another type ofdevice that serves as a data storage facility. As indicated previously,these various drives and controllers are optional devices. Additionally,the memory devices 925 may be configured to include individual files forstoring any software modules or instructions, auxiliary data, incidentdata, common files for storing groups of contingency tables and/orregression models, or one or more databases for storing the informationas discussed above.

Program instructions, software or interactive modules for performing anyof the functional steps associated with the processes as described abovemay be stored in the ROM 910 and/or the RAM 915. Optionally, the programinstructions may be stored on a tangible computer readable medium suchas a compact disk, a digital disk, flash memory, a memory card, a USBdrive, an optical disc storage medium, a distributed storage medium suchas a cloud-based architecture, and/or other recording medium.

A display interface 930 may permit information from the bus 900 to bedisplayed on the display 935 in audio, visual, graphic or alphanumericformat. Communication with external devices may occur using variouscommunication ports 940. A communication port 940 may be attached to acommunications network, such as the Internet, a local area network or acellular telephone data network.

The hardware may also include an interface 945 which allows for receiptof data from input devices such as a keyboard 950 or other input device955 such as a remote control, a pointing device, a video input deviceand/or an audio input device.

FIG. 10 illustrates an example of a lit environment 1000, in this case afootball field that is to be an illuminated surface 1001 in a stadium,in which a set of LED lighting devices 1051-1058 are positioned atvarious locations and which direct light to the illuminated surface1001. The sensors (represented by dark circles on the illuminatedsurface 1001) may measure characteristics of the light and send theinformation to a controller. Thus, the illumination devices arepositioned at various locations of an entertainment facility, and thesensors are located proximate to a playing surface or stage of thefacility.

Each sensor may be assigned to a zone—i.e., an area of the illuminatedsurface—and may thus gather characteristics of light directed to thezone, such as color temperature, D_(uv) and intensity. When a systemcontroller receives a command to implement a scene at a particular zone,the controller will access a data set and receive parameters thatcorrespond to the scene, such as one or more areas affected by thescene, color temperatures and light intensities associated with eacharea for the scene, and an identification of the lighting devices thatdirect light to areas of the scene. For example, the controller mayaccess a data storage facility with various scene data, retrieve a setof scene data that corresponds to the selected scene, and extract fromthe scene data an identification of the lighting devices that correspondto the scene. The controller may then cause the affected light fixturesto automatically alter their color temperature and/or light intensityoutput so that the desired color temperatures and light intensities aredirected to each area of the illuminated surface that is part of thescene. Optionally, if a sensor for an area detects that the colortemperature or intensity (illuminance level) has deviated from thevalues assigned to that area for the scene, then when the controllerreceives this information it may generate a command that causes one ormore of the lighting devices to alter their color temperature orbrightness of output light in order to achieve the assigned values inthe affected area.

The sensors such as those shown in FIG. 10 may be installed on a surfaceand used to collect light measurement data and transmit the data to thecontroller to make real-time adjustments during an event. Alternatively,or in addition the sensors may be used for calibration of the system orcollection of data to define a scene. For example, a sensor may bepositioned in a location, and various lighting devices may be directedto the location while the sensor collects color temperature, intensity,CRI, D_(uv), or other light characteristic data. The data may becollected by manually placing the sensor at each target location, or thesensor may be placed on or in a robotic transport device, such as amanually operated vehicle or drone. Optionally, the vehicle or drone maybe programmed with location and route data so that it automaticallymoves throughout the facility to collect data. When the sensor reacheseach location, it may be positioned at various angles with respect tothe plane of the ground to collect measure characteristics of lightreceived at various angles. For example, the sensor may be positioned sothat it receives light from a horizontal direction, a verticaldirection, and/or any angle in between. The positioning may occurmanually, or the robotic transport device may include one or moremotors, axles or other components that can rotate the sensor andautomatically collect light from various angles.

If the sensed data does not match the desired data for a location, thenthe lights may be adjusted using drive current variation or PWMtechniques such as those described above until the desiredcharacteristics are detected. When the desired characteristics aredetected, the system may save a record of the lighting system parameters(e.g., drive currents and PWM settings for each light fixture associatedwith the scene) to the set of scene data. In this way, later, when auser of the user interface selects a scene, all of the data for alllighting devices associated from the scene may be retrieved from thedata set, and commands to cause each affected lighting device to operateaccording to the scene's parameters may be sent to the lighting devices.

The features and functions disclosed above, as well as alternatives, maybe combined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations or improvements may be made by those skilled in the art, eachof which is also intended to be encompassed by the disclosedembodiments.

The invention claimed is:
 1. A lighting system, comprising: a pluralityof light emitting diode (LED) illumination devices, each of whichcomprises a first group of LEDs of a first color temperature and asecond group of LEDs of a second color temperature; a plurality ofillumination device drivers, wherein each illumination device driver isconfigured to control a corresponding LED illumination device; and asensor comprising a D_(uv) sensor that is configured to measure a D_(uv)value of light received from the devices in a location of an environmentthat is illuminated by the LED illumination devices; a wirelesstransmitter that is connected to the sensor and configured to transmitmeasurements detected by the sensor; and a hardware device containingprogramming instructions that are configured to cause a processor toperform a calibration event by: detecting when the measured D_(uv) valueof the light received by the sensor deviates from a desired valuecorresponding to a desired color temperature, in response to detectingthat the value of the measured D_(uv) value deviates from the desiredvalue, generating commands to cause the device drivers for each of theLED illumination devices to control the first group of LEDs and thesecond group of LEDs in its corresponding illumination device so thatthe desired color temperature of light will be received at the locationwhile maintaining a substantially constant illuminance level at thelocation, and when the processor receives measurements from the wirelesstransmitter indicating that the measured D_(uv) value corresponds to thedesired value, storing a record of lighting system parameters for ascene to a data set.
 2. The lighting system of claim 1, wherein thecommands that cause the device drivers to control the first group ofLEDs and the second group of LEDs in each illumination device so thatthe desired color temperature of light will be received at the locationcomprise instructions to increase drive current delivered to the firstgroup of LEDs and decrease drive current delivered to the second groupof LEDs in each illumination device.
 3. The lighting system of claim 1,wherein the commands that cause the device drivers to control the firstgroup of LEDs and the second group of LEDs so that the illuminance levelremains substantially constant comprise at the location comprisecommands to: automatically reduce brightness of one of the groups ofLEDs by decreasing a width of voltage pulses applied to that group ofLEDs or increasing spacing between voltage pulses applied to that groupof LEDs; and automatically increase brightness of the other group ofLEDs by increasing a width of voltage pulses applied to that group ofLEDs or decreasing spacing between voltage pulses applied to that groupof LEDs.
 4. The lighting system of claim 1, wherein: the sensor furthercomprises a light intensity sensor; and the programming instructions areconfigured so that: when a value of measured light intensity exceeds athreshold, the device drivers will reduce brightness of a group of theLEDs by decreasing a width of voltage pulses applied to the group ofLEDs or increasing spacing between voltage pulses applied to the groupof LEDs to maintain an illuminance level at the location within thethreshold; and when the value of measured light intensity is below thethreshold, the device drivers will automatically increase the brightnessof a group of the LEDs by increasing a width of voltage pulses appliedto the group of LEDs or decreasing spacing between voltage pulsesapplied to the group of LEDs to maintain the illuminance level at thelocation within the threshold.
 5. The lighting system of claim 1,wherein the programming instructions to maintain the substantiallyconstant illuminance level at the location comprise instructions to:reduce brightness of one of the group of LEDs by decreasing a width ofvoltage pulses applied to that group of LEDs or increasing spacingbetween voltage pulses applied to that group of LEDs; and increasebrightness of the other group of LEDs by increasing a width of voltagepulses applied to that group of LEDs or decreasing spacing betweenvoltage pulses applied to that group of LEDs.
 6. The lighting system ofclaim 1, wherein the illumination devices are positioned at variouslocations of an entertainment facility, and the sensors are locatedproximate to a playing surface or stage of the facility.
 7. The lightingsystem of claim 1, further comprising programming instructions that areconfigured to cause a processor to: receive, from a user interface, aselection of the scene; use the data set to generate commands to causethe device drivers for each of the identified LED illumination devicesto control their corresponding LED illumination devices according to thelighting system parameters for the scene; and transmit the commands tothe device drivers for the LED illumination devices that correspond tothe scene so that the LED illumination devices will operate according tothe lighting system parameters for the scene.
 8. The lighting system ofclaim 7, wherein: the system further comprises a color temperaturesensor; and the commands are configured so that when a value of colortemperature detected by the color temperature sensor has moved above orbelow a threshold, the system will control drive currents delivered tothe first group of LEDs and the second group of LEDs so that the lightdetected by the sensor at the location will exhibit a color temperaturethat is within the threshold.
 9. The lighting system of claim 8, whereinthe commands to cause the device drivers for each of the identified LEDillumination devices to control their corresponding LED illuminationdevices according to the lighting system parameters for the scenecomprise commands to: reduce brightness of one of the groups of LEDs bydecreasing a width of voltage pulses applied to that group of LEDs orincreasing spacing between voltage pulses applied to that group of LEDs;and increase brightness of the other group of LEDs by increasing a widthof voltage pulses applied to that group of LEDs or decreasing spacingbetween voltage pulses applied to that group of LEDs.
 10. A method ofcontrolling light directed to a surface, comprising: operating aplurality of light emitting diode (LED) illumination devices to directlight to a surface of a facility, wherein each illumination devicecomprises: a first group of LEDs of a first color temperature and asecond group of LEDs of a second color temperature, and a device driverconfigured to control the LED illumination device; and by a controller,performing a calibration event by: receiving a D_(uv) value of lightdetected by a D_(uv) sensor that is proximate to the surface; detectingwhen the received D_(uv) value deviates from a desired valuecorresponding to a desired color temperature, in response to detectingthat the received D_(uv) value deviates from the desired value, causingthe device driver for each of the LED illumination devices to controldrive currents delivered to the first group of LEDs and the second groupof LEDs of its corresponding illumination device so that the desiredcolor temperature of light will be directed to a location of the sensorwhile maintaining a substantially constant illuminance level at thelocation, and when the controller receives measurements from a wirelesstransmitter indicating that the measured D_(uv) value corresponds to thedesired value, store a record of lighting system parameters for a sceneto a data set.
 11. The method of claim 10, wherein causing the devicedrivers to control the first group of LEDs and the second group of LEDsin their illumination devices so that the desired color temperature oflight will be received at the location comprises increasing drivecurrent delivered to the first group of LEDs and decreasing drivecurrent delivered to the second group of LEDs in each illuminationdevice.
 12. The method of claim 10, wherein causing the device driversto control the first group of LEDs and the second group of LEDs so thatthe illuminance level remains substantially constant at the locationcomprises: automatically reducing brightness of one of the groups ofLEDs by decreasing a width of voltage pulses applied to that group ofLEDs or increasing spacing between voltage pulses applied to that groupof LEDs; and automatically increasing brightness of the other group ofLEDs by increasing a width of voltage pulses applied to that group ofLEDs or decreasing spacing between voltage pulses applied to that groupof LEDs.
 13. The method of claim 10, wherein: the sensor furthercomprises a color temperature sensor; and detecting when a value ofcolor temperature detected by the color temperature sensor deviates froma desired value and causing the device drivers to control drive currentscomprise: when the value of color temperature detected by the sensor hasmoved above or below a threshold, altering drive currents delivered tothe first group of LEDs and the second group of LEDs so that the lightdetected by the sensor at the location will exhibit a color temperaturethat is within the threshold.
 14. The method of claim 13, whereinmaintaining the substantially constant illuminance level at the locationcomprises: reducing brightness of one of the groups of LEDs bydecreasing a width of voltage pulses applied to that group of LEDs orincreasing spacing between voltage pulses applied to that group of LEDs;and increasing brightness of the other group of LEDs by increasing awidth of voltage pulses applied to that group of LEDs or decreasingspacing between voltage pulses applied to that group of LEDs.
 15. Themethod of claim 10, wherein maintaining the substantially constantilluminance level at the location comprises: reducing brightness of oneof the groups of LEDs by decreasing a width of voltage pulses applied tothat group of LEDs or increasing spacing between voltage pulses appliedto that group of LEDs; and increasing brightness of the other group ofLEDs by increasing a width of voltage pulses applied to that group ofLEDs or decreasing spacing between voltage pulses applied to that groupof LEDs.
 16. The method of claim 10, wherein the facility is anentertainment facility, and the sensors are located proximate to aplaying surface or stage of the facility.
 17. The method of claim 10,further comprising, by the controller: receiving a selection of thescene; using the data set to generate commands to cause the devicedrivers for each of the identified LED illumination devices to controltheir corresponding LED illumination devices according to the lightingsystem parameters for the scene; and transmitting the commands to thedevice drivers for the LED illumination devices that correspond to thescene so that the LED illumination devices will operate according to thelighting system parameters for the scene.
 18. The method of claim 17,wherein: the commands comprise commands to determine when a lightintensity sensor has detected when a value of measured light intensitydeviates from a desired value; and the method further comprises: whenthe value of measured light intensity exceeds a threshold, causing thedevice drivers to reduce brightness of a group of the LEDs by decreasinga width of voltage pulses applied to the group of LEDs or increasingspacing between voltage pulses applied to the group of LEDs to maintainan illuminance level at the location within the desired range, and whenthe value of measured light intensity is below the threshold, causingthe device drivers to increase brightness of a group of the LEDs byincreasing a width of voltage pulses applied to the group of LEDs ordecreasing spacing between voltage pulses applied to the group of LEDsto maintain the illuminance level at the location within the desiredrange.